Assessing the impacts of land use/land cover changes on hydrological processes in Southern Ethiopia: The SWAT model approach

The change in land use and land cover (LULC) due to human activities is a major cause of hydrological process changes in watersheds. This study assesses the effects of LULC changes on the hydrological processes in the Bilate catchment, located in southern Ethiopia. Landsat images of 1986, 2002, and 2018 were used to classify LULC through supervised classification. The Soil and Water Assessment Tool (SWAT) evaluated the hydrological responses to LULC changes. Results indicate an increase in built-up areas (0.70%), water bodies (0.19%), cultivated land (10.54%), and barren land (1.265%) from 1986 to 2018. Conversely, the forest (8.52%) and grazing (3.18%) areas declined. An increase in water leaving the root zone (962.02 mm/year), potential evapotranspiration (593.85 mm/year), actual evapotranspiration (201.71 mm/year), and surface runoff (514.86 mm/year) was observed, while soil water content (1423.25 mm/year) decreased at the catchment level. The declining soil water content and increasing actual and potential evapotranspiration could result in a water shortage for crop production. The impact of LULC changes on hydrology provides vital knowledge for integrated LULC and water resource management. Water resource development planning must consider LULC changes to achieve sustainable development in the catchment.